Patent GB-1334298-A (GB)
Title: Telecommunications networks
IPC: H04Q3/00
Filed: 1971-10-14
Abstract: 1334298 Automatic exchange systems SIEMENS AG 14 Oct 1971 [16 Oct 1970] 47814/71 Heading H4K In a multi-exchange system having subscribers who retain their personal directory numbers irrespective of the exchange to which they are currently connected and in which each exchange includes a store containing the directory numbers of the subscribers connected to the particular exchange, subscribers can automatically withdraw from or report to an exchange by transmitting an appropriate signal which may include a special code followed by the subscriber's  number, the reporting procedure including an operation whereby the exchange reported to conducts a special hunting process whereby the stores of all exchanges in the system are searched for subscribers having the same number as the reporting subscriber and wherein, if the hunting process fails to find a corresponding number, the number of the reporting subscriber is recorded in the store of the exchange reported to, and the subscriber is thereby connected to the system. The reporting procedure: when a newly connected subscriber TSt wishes to report to his new exchange VSt that he is now connected, he emits a reporting signal, e.g. by pressing a special report key or by dialling a special number, and then dials his own subscriber number. Reporting signal analyser An responds to the reporting signal and closes switch S 1 so that the subscriber's number passes from line in into a receiving store R. The number is then transmitted from this store via line s to all the other  exchanges to determine whether any other exchange has this number stored. If the number is not found, a corresponding signal is received back from all the exchanges and switch S2 is supplied with an actuating signal via line f. The number of the reporting subscriber is then  transferred to the main exchange store RA- the subscriber number-connection state converter, where it is stored along with the identity of the exchange terminal to which the subscriber is connected or the particular time or frequency channel together with the particular t.d.m. or frequency multiplex line via which the subscriber may be reached. The reporting subscriber can check that he has been connected by lifting his hand set. If the search is negative but the number has not yet been transferred to store RA, he obtains the non-connected tone; once the number has been stored he obtains the dialling tone. If an identical number is found during the hunting process he will obtain the ringing tone or engaged tone. Further subscriber numbers, e.g. for call diversion or of a conference connection, can be recorded by a subscriber under his connection state in store RA by emission of a special signal and the corresponding number. No hunting process takes place in such cases. The withdrawal procedure: transmission of a withdrawal signal followed by dialling of his own subscriber number is detected by a withdrawal signal-analysis circuit Ab which transmits an erasing signal to store RA which removes the appropriate signal from store. If the subscriber now picks up his hand set the non-connected tone is received. All other numbers stored under the connection state of the withdrawing subscriber may also be erased. Withdrawal may also be effected after moving to a new exchange area with the aid of an operator of the relevant exchange. British Specifications 1,176,514 and 1,286,358 and German Specifications 1,949,375 and 1,487,869 are referred to. The latter German Patent describes a prior art arrangement in which each subscriber who may wish to change his exchange frequently is assigned a so-called subscriber number plug which is plugged into a plug connection panel belonging to the particular exchange. For this subscriber to change his position or type of connection within the network, he must withdraw his subscriber number plug from the connection panel of the present exchange and insert the plug into a corresponding receiver of the connection panel of the new exchange. The previously described arrangement obviates this necessity.